Enhanced control using ai in apparatus having ir camera heat detection system

ABSTRACT

A method of joining electronic components to an electronic substrate in an apparatus includes: (1) transporting electronic substrates through a chamber housing including a tunnel extending through multiple processing zones; (2) detecting temperatures of the electronic substrates passing proximate to a heat detection system including at least one temperature sensor coupled to the chamber housing; (3) receiving temperature data from the heat detection system with a controller coupled to the multiple processing zones, the conveyor, and the heat detection system; (4) determining, by the controller, with reference to the detected temperatures of the electronic substrates, an adjustment to at least one of (a) a heat setting of a heating element within the chamber housing, (b) a speed of the conveyor, and (c) an operational speed of a blower within the chamber housing; and (5) performing the determined adjustment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to both U.S.Provisional Application Ser. No. 63/120,971, titled “APPARATUS HAVINGCLOSED LOOP IR CAMERA HEAT DETECTION SYSTEM AND METHOD,” filed on Dec.3, 2020; and to U.S. patent application Ser. No. 17/511,907, titled“APPARATUS HAVING CLOSED LOOP IR CAMERA HEAT DETECTION SYSTEM ANDMETHOD,” filed on Oct. 27, 2021, both of which are incorporated hereinby reference in their entirety for all purposes.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

This application relates generally to the surface mount of electroniccomponents onto a printed circuit board by employing an assemblyprocess, such as a reflow process, a wave soldering process, and/or aselective soldering process, and more particularly to an apparatus thatis designed to control heat applied to the printed circuit board duringthe assembly process.

2. Discussion of Related Art

In the fabrication of printed circuit boards, electronic components areoften surface mounted to a bare board by a process known as “reflowsoldering.” In a typical reflow soldering process, a pattern of solderpaste is deposited onto the circuit board, and the leads of one or moreelectronic component are inserted into the deposited solder paste. Thecircuit board is then passed through an oven where the solder paste isreflowed (i.e., heated to a melt or reflow temperature) in the heatedzones and then cooled in a cooling zone to electrically and mechanicallyconnect the leads of the electronic component to the circuit board. Theterm “circuit board” or “printed circuit board,” as used herein,includes any type of substrate assembly of electronic components,including, for example, wafer substrates.

As stated above, present day reflow ovens have heating and coolingchambers. To achieve a consistent reflow process profile, heat appliedto the electronic components and the circuit boards is preciselycontrolled to ensure proper mechanical and electrical connection of theelectronic components to the circuit boards.

Moreover, in the fabrication of printed circuit boards, electroniccomponents can be mounted to circuit boards by a process known as “wavesoldering.” In a typical wave solder machine, the circuit boards aremoved by a conveyor on an inclined path past a fluxing station, apre-heating station, and finally a wave soldering station. At the wavesoldering station, a wave of solder is caused to well upwardly (by meansof a pump) through a wave solder nozzle and contact portions of theprinted circuit board to be soldered. As with reflow ovens, wave soldermachines (and selective solder machines) require that the heat of eachzone is precisely controlled to ensure proper mechanical and electricalconnection of the electronic components to the circuit boards.

For both reflow ovens and wave (and selective) solder machines,controlling heat in the zones of the respective equipment is veryimportant for optimum performance. For example, undesirable temperaturevariance can cause warpage of the circuit board and unreliableconnections between the electronic components and the circuit board.

SUMMARY OF THE DISCLOSURE

One aspect of the present disclosure is directed to a reflow ovenconfigured to join electronic components to an electronic substrate. Inone embodiment, the reflow oven comprises a chamber housing including atunnel extending through multiple processing zones, a conveyorconfigured to transport electronic substrates in the tunnel through themultiple processing zones, and a heat detection system including atleast one temperature sensor coupled to the chamber housing. The atleast one temperature sensor is configured to detect temperatures of theelectronic substrates passing proximate to the at least one temperaturesensor. The reflow oven further comprises a controller coupled to themultiple processing zones, the conveyor and the heat detection system.The controller is configured to receive temperature data from the heatdetection system.

Embodiments of the reflow oven further may include the at least onetemperature sensor having at least one sensor assembly. The at least onesensor assembly may include a support structure, a support bracketcoupled to the support structure, and an IR camera secured to thesupport bracket. The support structure may include a shroud that ismounted on the mounting plate. The shroud may be configured to surroundan opening within a top of the tunnel to enable a temperature of thetunnel to be sensed by the IR camera. The support bracket may include aport to connect to a source of inert gas. The support bracket mayinclude a glass cover to protect the IR camera. The support bracket maybe configured to mount the IR camera on top of the tunnel at a desiredheight and a desired orientation to achieve a full field of view. The atleast one sensor assembly may include multiple IR cameras to measure twoor more separate locations within select locations within the tunnel.The heat detection system may be configured with the controller toprovide closed loop control of the zone temperatures of the multipleprocessing zones using the sensor assembly. The at least one sensorassembly may be configured to obtain temperature data at specificelectronic substrate level locations and in certain processing zones ofthe reflow soldering oven. Temperature data may be used to provideelectronic substrate traceability in which data on a particularelectronic substrate is provided on a display associated with thecontroller. Temperature data may be used to find hot spot zones/levelswithin the reflow soldering oven. Temperature data may be used tooptimize the performance of the reflow soldering oven and/or to providedownstream input of processing equipment and/or to determine start andend times of scanning performed by the at least one sensor assembly onelectronic substrates and/or to generate electronic substrate profilesabove and below the electronic substrate. The closed loop control mayinclude controlling a speed of the conveyor in the multiple processingzones. The electronic substrates each may include a bar code that isscanned by a bar code scanner. The controller may be configured toachieve a scan mode to measure the temperature of components of theelectronic substrates as the electronic substrates travel on theconveyor through the reflow soldering oven.

Another aspect of the present disclosure is directed to method ofjoining electronic components to an electronic substrate in a reflowoven. In one embodiment, the method comprises: transporting electronicsubstrates through a chamber housing including a tunnel extendingthrough multiple processing zones; detecting temperatures of theelectronic substrates passing proximate to a heat detection systemincluding at least one temperature sensor coupled to the chamberhousing; and receiving temperature data from the heat detection systemwith a controller coupled to the multiple processing zones, the conveyorand the heat detection system.

Embodiments of the method further may include scanning a bar codeassociated with each substrate by a bar code scanner and/or controllingthe reflow soldering oven to achieve a scan mode to measure thetemperature of components of the electronic substrates as the electronicsubstrates travel on the conveyor through the reflow soldering oven. Theheat detection system may be configured with the controller to provideclosed loop control of the zone temperatures of the multiple processingzones using the sensor assembly. The at least one sensor assembly may beconfigured to obtain temperature data at specific electronic substratelevel locations and in certain processing zones of the reflow solderingoven. Temperature data may be used to provide electronic substratetraceability in which data on a particular electronic substrate isprovided on a display associated with the controller. Temperature datamay be used to find hot spot zones/levels within the reflow solderingoven. Temperature data may be used to optimize the performance of thereflow soldering oven and/or to provide downstream input of processingequipment and/or to determine start and end times of scanning performedby the at least one sensor assembly on electronic substrates and/or togenerate electronic substrate profiles above and below the electronicsubstrate. The closed loop control may include controlling a speed ofthe conveyor in the multiple processing zones. The method further mayinclude scanning a bar code associated with each substrate by a bar codescanner. The method further may include controlling the reflow solderingoven to achieve a scan mode to measure the temperature of components ofthe electronic substrates as the electronic substrates travel on theconveyor through the reflow soldering oven.

Yet another aspect of the present disclosure is directed to a wavesolder or selective solder machine configured to join electroniccomponents to an electronic substrate. In one embodiment, the reflowoven comprises a chamber housing including a tunnel extending throughmultiple processing zones, a conveyor configured to transport electronicsubstrates in the tunnel through the multiple processing zones, and aheat detection system including at least one temperature sensor coupledto the chamber housing. The at least one temperature sensor isconfigured to detect temperatures of the electronic substrates passingproximate to the at least one temperature sensor. The wave solder orselective solder machine further comprising a controller coupled to themultiple processing zones, the conveyor and the heat detection system.The controller is configured to receive temperature data from the heatdetection system. The at least one temperature sensor may include atleast one sensor assembly. The at least one sensor assembly may includea support structure, a support bracket coupled to the support structure,and an IR camera secured to the support bracket. The support structuremay include a mounting plate that is positioned on a top of the tunneland a shroud that is mounted on the mounting plate. The shroud may beconfigured to surround an opening within the mounting plate to enable atemperature of the tunnel to be sensed by the IR camera. The supportbracket may include a port to connect to a source of inert gas. Thesupport bracket may include a glass cover to protect the IR camera. Thesupport bracket may be configured to mount the IR camera on top of thetunnel at a desired height and a desired orientation to achieve a fullfield of view. The at least one sensor assembly may include multiple IRcameras to measure two or more separate locations within selectlocations within the tunnel. The heat detection system may be configuredwith the controller to provide closed loop control of the zonetemperatures of the multiple processing zones using the at least onesensor assembly. The at least one sensor assembly may be configured toobtain temperature data at specific electronic substrate level locationsand in certain processing zones of the reflow soldering oven.Temperature data may be used to provide electronic substratetraceability in which data on a particular electronic substrate isprovided on a display associated with the controller. Temperature datamay be used to find hot spot zones/levels within the wave solder orselective solder machine. Temperature data may be used to optimize theperformance of the wave solder or selective solder machine and/or toprovide downstream input of processing equipment and/or to determinestart and end times of scanning performed by the at least one sensorassembly on electronic substrates and/or to generate electronicsubstrate profiles above and below the electronic substrate. The closedloop control may include controlling a speed of the conveyor in themultiple processing zones. The electronic substrates each may include abar code that is scanned by a bar code scanner. The controller may beconfigured to achieve a scan mode to measure the temperature ofcomponents of the electronic substrates as the electronic substratestravel on the conveyor through the wave solder or selective soldermachine.

Another aspect of the present disclosure is directed to a method ofjoining electronic components to an electronic substrate in a wavesolder or selective solder machine. In one embodiment, the methodcomprises: transporting electronic substrates through a chamber housingincluding a tunnel extending through multiple processing zones;detecting temperatures of the electronic substrates passing proximate toa heat detection system including at least one temperature sensorcoupled to the chamber housing; and receiving temperature data from theheat detection system with a controller coupled to the multipleprocessing zones, the conveyor and the heat detection system.

Embodiments of the method further may include scanning a bar codeassociated with each substrate by a bar code scanner and/or controllingthe machine to achieve a scan mode to measure the temperature ofcomponents of the electronic substrates as the electronic substratestravel on the conveyor through the machine. The heat detection systemmay be configured with the controller to provide closed loop control ofthe zone temperatures of the multiple processing zones using the sensorassembly. The at least one sensor assembly may be configured to obtaintemperature data at specific electronic substrate level locations and incertain processing zones of the machine. Temperature data may be used toprovide electronic substrate traceability in which data on a particularelectronic substrate is provided on a display associated with thecontroller. Temperature data may be used to find hot spot zones/levelswithin the machine. Temperature data may be used to optimize theperformance of the machine and/or to provide downstream input ofprocessing equipment and/or to determine start and end times of scanningperformed by the at least one sensor assembly on electronic substratesand/or to generate electronic substrate profiles above and below theelectronic substrate. The closed loop control may include controlling aspeed of the conveyor in the multiple processing zones.

Another aspect of the present disclosure is directed to an apparatusconfigured to join electronic components to an electronic substrate. Inone embodiment, the apparatus comprises a chamber housing including atunnel extending through multiple processing zones, a conveyorconfigured to transport electronic substrates in the tunnel through themultiple processing zones, and a heat detection system including atleast one temperature sensor coupled to the chamber housing. The atleast one temperature sensor is configured to detect temperatures of theelectronic substrates passing proximate to the at least one temperaturesensor. The apparatus further includes a controller coupled to themultiple processing zones, the conveyor and the heat detection system.The controller is configured to receive temperature data from the heatdetection system.

Yet another aspect of the disclosure is directed to a method of joiningelectronic components to an electronic substrate in an apparatus. In oneembodiment, the method comprises: transporting electronic substratesthrough a chamber housing including a tunnel extending through multipleprocessing zones; detecting temperatures of the electronic substratespassing proximate to a heat detection system including at least onetemperature sensor coupled to the chamber housing; and receivingtemperature data from the heat detection system with a controllercoupled to the multiple processing zones, the conveyor and the heatdetection system.

Another aspect of the present disclosure is directed to method ofjoining electronic components to an electronic substrate in anapparatus. In one embodiment, the method comprises: (1) transportingelectronic substrates through a chamber housing including a tunnelextending through multiple processing zones; (2) detecting temperaturesof the electronic substrates passing proximate to a heat detectionsystem including at least one temperature sensor coupled to the chamberhousing; (3) receiving temperature data from the heat detection systemwith a controller coupled to the multiple processing zones, theconveyor, and the heat detection system; (4) determining, by thecontroller, with reference to the detected temperatures of theelectronic substrates, an adjustment to at least one of (a) a heatsetting of a heating element within the chamber housing, (b) a speed ofthe conveyor, and (c) an operational speed of a blower within thechamber housing; and (5) performing the determined adjustment. Yetanother aspect of the disclosure is directed to a correspondingapparatus. Yet another aspect of the disclosure is directed to acorresponding computer program product.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a perspective view of a reflow soldering oven of an embodimentof the present disclosure;

FIG. 2 is a schematic view of the reflow soldering oven shown in FIG. 1;

FIG. 3 is a perspective view of a portion of the reflow soldering ovenshowing a heat detection system of an embodiment of the presentdisclosure;

FIG. 4 is a perspective view of an IR camera assembly of the heatdetection system shown in FIG. 3 ;

FIG. 5 is a perspective view of the IR camera assembly mounted on a topwall of a tunnel of the reflow soldering oven;

FIG. 6 is a perspective view of an IR camera mounted on a gantry ofanother embodiment of the heat detection system;

FIG. 7 is a schematic view of a wave solder machine of an embodiment ofthe disclosure;

FIG. 8 is a side elevational view of the wave solder machine withexternal packaging removed to reveal internal components of the wavesolder machine;

FIG. 9 is a perspective view of an IR camera assembly of the heatdetection system associated with the wave solder machine;

FIG. 10 is perspective view of the IR camera assembly shown in FIG. 9 ;

FIG. 11 is a block diagram depicting a system, apparatus, computerprogram product, and associated data structures according to variousembodiments of the present disclosure; and

FIG. 12 is a flowchart depicting a method according to variousembodiments of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Solder paste is routinely used in the assembly of printed circuitboards, where the solder paste is used to join electronic components tothe circuit board. Solder paste includes solder for joint formation andflux for preparing metal surfaces for solder attachment. The solderpaste may be deposited onto the metal surfaces (e.g., electronic pads)provided on the circuit board by using any number of applicationmethods. In one example, a stencil printer may employ a squeegee toforce the solder paste through a metallic stencil laid over an exposedcircuit board surface. In another example, a dispenser may dispensesolder paste material onto specific areas of the circuit board. Leads ofan electronic component are aligned with and impressed into the solderdeposits to form the assembly. In reflow soldering processes, the solderis then heated to a temperature sufficient to melt the solder and cooledto permanently couple the electronic component, both electrically andmechanically, to the circuit board. The solder typically includes analloy having a melting temperature lower than that of the metal surfacesto be joined. The temperature also must be sufficiently low so as to notcause damage to the electronic component. In certain embodiments, thesolder may be a tin-lead alloy. However, solders employing lead-freematerials may also be used.

Temperature control of the soldering process is very important. In oneembodiment of the present disclosure, a heat detection system havingseveral infrared (IR) cameras is used to precisely measure thetemperature of the circuit board within strategic locations of thereflow soldering oven. The information obtained from the IR cameras ofthe heat detection system can be used to provide closed-loop control ofthe reflow oven to ensure proper connections between electroniccomponents and circuit boards. Other types of temperature measuringdevices can be employed in place of the IR cameras. For example, lasertemperature sensors can be used as part of the heat detection system.Moreover, the techniques described herein can be used for other types ofcircuit board processing equipment, such as wave solder machines andselective solder machines, to achieve improved temperature control.

For the purposes of illustration only, and not to limit the generality,the present disclosure will now be described in detail with reference tothe accompanying figures. This disclosure is not limited in itsapplication to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in thedrawings. The principles set forth in this disclosure are capable ofother embodiments and of being practiced or carried out in various ways.Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” “having,” “containing,” “involving,” andvariations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.

Reflow Soldering Oven

In the reflow process, a circuit printed board is heated forapproximately 3-5 minutes according a pre-defined temperature profile.The complete assembly (including board material, components, and solderpaste) should reach a minimum reflow temperature, but should not beoverheated. Overheating may damage components and result in solderdefects. To achieve this heating curve, the reflow soldering ovencontains multiple heating and cooling zones. The zones blow hot or coldgas toward the circuit board. The gas temperature set-points of thesezones in combination with the conveyor speed defines the final heatingprofile of the circuit board assembly.

To ensure that the reflow soldering oven is operating correctly, aprinted circuit board is provided with thermocouples to record thetemperature of the circuit board over time. The thermocouples are placedon the coldest and hottest locations of the circuit board assembly andon critical components to make sure that the components are notoverheated. Once the set-points and conveyor speed are determined to bewithin an acceptable specification, the oven contains controls andthermal probes to maintain the temperatures of the zones within theacceptable boundaries. During production there may be circuit boardswith thermocouples that are run through the reflow soldering oven toassure that all predefined conditions are still within the acceptablespecification. A shortcoming of existing process control is that thereis no temperature control on the circuit board assemblies during thereflow process. Inspection of the components and solder joints of thecircuit boards occur after soldering; however, there is no verificationduring the time the circuit boards are heated.

Existing process control is directed to maintaining the zonetemperatures and conditions within specification using thermo probesthat measure the gas temperatures but not the actual temperature on thecircuit board assemblies. There is thermal profiling hardware availablethat have software tools that help to define, measure, monitor andimprove thermal processes for electronic manufacturing services. Thesesystems make the reflow soldering ovens smarter and reduce defectsbecause of better process control. The intelligent software makesmodifications to the oven settings when required to guarantee consistentboard temperatures and solder quality.

Despite of the intelligent systems and process control of the reflowsoldering oven, there is no verification of the actual temperatures ofthe circuit board assemblies during soldering. The implementation of aheat detection system that can obtain thermal images of the circuitboard assemblies during the reflow will add value to process controlpreventing component damage and reducing solder defects.

Embodiments of the present disclosure are directed to a heat detectionsystem having several IR camera assemblies strategically positionedwithin the reflow soldering oven to obtain closed loop temperaturecontrol of the oven. In one embodiment, a lens of the IR camera assemblyis kept clean to enable making accurate temperature images. The IRcamera assembly includes a special chamber in front of the lens wherenitrogen is purged into to generate an overpressure avoiding the fluxcontaminated gasses to condensate on the lens. Another method disclosedherein to maintain a clean lens from flux residues is to have atransparent foil in front of the lens on a roll system. Once the foil isdirty, the roll turns to have a new clean transparent spot.Additionally, the reflow soldering oven may contain a catalyst to cleanthe gas in the zones.

Embodiments of the heat detection system include the use of thermalimages to be part of a closed loop system that controls the reflowprocess. Data from the thermal images are integrated in an intelligentcontrol system of the reflow soldering oven. The camera can be 3Dthermal camera or a common 2D camera. The data generated (temperaturesof different areas, components, solder paste and board material) can beused for traceability and corrective actions. The reflow process canhave multiple cameras. A thermal image scan is a snapshot of the reflowprocess. However, when there are multiple cameras installed, thecollection of snapshots can be used to calculate important processparameters like time above liquidus and peak temperatures. This data canbe correlated to defect levels and preventive actions can be sent toprinters or dispensers or pick-and-place machines to make necessarymodifications.

The image scan also can signal deviations and the reflow soldering ovencan respond accordingly. If temperatures are too low or too high,different actions can be taken, such as changing conveyor speed oradjusting the fan speed of one or more heating zones to increase ordecrease the heat transfer. Other methods to make temperaturecorrections are to temporarily stopping the circuit board to becomewarmer or pushing the circuit board through the zone to achieve ashorter heating time when the circuit board is too hot. These smallcorrections require free space between the circuit boards. If the boardis too cold, IR lamps can be installed in the zones behind a scanner towarm up that particular circuit board faster to be in specification. Thetracking system of the oven transport should keep track on the positionsof the circuit boards in the reflow soldering oven to make the scan atthe right moment. Typically, the conveyor has an encoder or other devicethat controls speed and defines a position of the circuit board. In oneembodiment, additional sensors can be installed near the scanners tolocate the circuit boards. The circuit boards can be configured to havebarcodes, RFID tags, or some other type of identification traceability.

Embodiments of the heat detection system are configured to obtain imagescans to show component alignment during the reflow process and toanalyze component movement defects. For example, if there are multiplescanners in the reflow soldering oven, positions within the reflowsoldering oven can be defined where the component moves and this mayhelp to avoid this type of defect. Further actions can includereplacement of a fan or reducing a fan speed in specific zones of theoven.

Embodiments of the heat detection system further are configured toobtain temperature profiles of circuit boards at strategic points withinthe reflow soldering oven. This is more accurate than thermocoupleprofiling, which only returns temperatures of the probes. The positionof the probes may not be the most critical spots on the circuit boardassemblies and second the thermocouple attachment is critical. Athermocouple may become loose after some runs; however, IR camerasremain accurate over time and are not limited by the number of samplesif the lens remains clean.

One embodiment of an exemplary reflow soldering apparatus for solderingthe circuit board assembly is shown in FIG. 1 . Such apparatuses aresometimes referred to as reflow ovens or reflow soldering ovens in theart of printed circuit board fabrication and assembly. The reflowsoldering oven, generally indicated at 10 in FIG. 1 , includes a reflowoven chamber 12 in the form of a thermally insulated tunnel defining apassage for pre-heating, reflowing and then cooling solder on a circuitboard passing therethrough. The reflow oven chamber 12 extends across aplurality of heating zones, including, in one example, three pre-heatzones 14, 16, 18 followed by three soak zones 20, 22, 24, each zonecomprising top and bottom heaters 26, 28, respectively. The soak zones20, 22, 24 are followed by four spike zones 30, 32, 34, 36, for example,which likewise include heaters 26, 28. And finally, three cooling zones38, 40, 42 follow the spike zones 30, 32, 34, 36. Other reflow solderingoven configurations can be provided.

A circuit board assembly 44, including deposited solder paste andelectronic components, is passed (e.g., left-to-right in FIG. 1 )through each zone of the thermally insulated reflow oven chamber 12 on afixed-speed conveyor, indicated by dashed lines at 46 in FIG. 1 ,thereby enabling controlled and gradual pre-heat, reflow and post-reflowcooling of the circuit board assembly. It should be understood that thefixed-speed conveyor 46 can be divided up between the zones and embodyvariable-speed conveyors. In the preliminary pre-heat zones 14, 16, 18,the board assembly is heated from ambient temperature up to the fluxactivation temperature, which may range between about 130° C. and about150° C. for lead-based solders and higher for lead-free solders.

In the soak zones 20, 22, 24, variations in temperature across thecircuit board assembly are stabilized and time is provided for theactivated flux to clean the component leads, electronic pads and solderpowder before reflow. Additionally, VOCs in the flux are vaporized. Thetemperature in the soak zones 20, 22, 24 is typically about 140° C. toabout 160° C. for lead-based solders and higher for lead-free solders.In certain embodiments, the circuit board assembly may spend aboutthirty to about forty-five seconds passing through the soak zones 20,22, 24.

In the spike zones 30, 32, 34, 36, the temperature quickly increases toa temperature above the melting point of the solder to reflow thesolder. The melting point for eutectic or near-eutectic tin-lead solderis about 183° C., with the reflow spike being typically set about 25° C.to about 50° C. above the melting point to overcome a pasty range ofmolten solder. For lead-based solders, a typical maximum temperature inthe spike zones is in the range of about 200° C. to about 220° C.Temperatures above about 225° C. may cause baking of the flux, damage tothe components and/or sacrifice joint integrity. Temperatures belowabout 200° C. may prevent the joints from fully reflowing. In oneembodiment, the circuit board assembly is typically maintained at atemperature within the spike zones 30, 32, 34, 36 above the reflowtemperature for about one minute.

Next, in the cooling zones 38, 40, 42, the temperature drops below thereflow temperature, and the circuit board assembly is cooledsufficiently to solidify the joints and thereby preserve joint integritybefore the circuit board assembly leaves the reflow oven chamber 12.

A flux extraction/filtration system (not shown) may be provided toremove contaminant materials from the gas generated by the reflowsoldering oven 10. In one embodiment, an input gas duct may be connectedto or between selected zones to provide fluid communication from thereflow oven chamber 12 to the flux extraction/filtration system. Anoutput gas duct may be connected to or between the selected zones toprovide fluid communication from the flux extraction/filtration systemback to the reflow oven chamber 12. In operation, a vapor stream iswithdrawn from the reflow oven chamber 12 through the input gas duct,through the system, then through the output gas duct and back to thereflow oven chamber. Similar constructions of input gas ducts, systemsand output gas ducts may be likewise positioned to withdraw vaporstreams from or between other zones of the reflow soldering oven 10.

The reflow soldering oven 10 further includes a controller 50 toautomate the operation of the several stations of the reflow solderingoven, including but not limited to the top heater 26 and the bottomheater 28 associated with the pre-heat zones 14, 16, 18, the soak zones20, 22, 24, the spike zones 30, 32, 34, 36, and the cooling zones 38,40, 42, in the well-known manner. As shown, the controller 50 mayinclude a display 52 with a user interface in which an operator of thereflow soldering machine 10 may control the operation of the machine.

In a certain embodiment, the controller 50 may be configured to use apersonal computer having a suitable operating system, such as aMicrosoft Windows® operating system provided by Microsoft Corporation,with application specific software to control the operation of thereflow soldering oven 10. The controller 50 may be networked with amaster controller that is used to control a production line forfabricating circuit boards. As will be described in greater detailbelow, the information obtained by the heat detection system can be usedby the controller 50 to optimize the performance of the reflow solderingoven 10. This optimization would include an elimination of warpage andthe better and more reliable securement of electronic components on thecircuit board assembly.

Referring to FIG. 3 , the reflow soldering oven 10 includes a heatdetection system, generally indicated at 60, that is configured todetect heat within the zones of the oven. In the shown embodiment, theheat detection system 60 includes several, e.g., three, sensorassemblies, such as IR camera assemblies, each generally indicated at62. In this example, a first IR camera assembly 62 a is positionedbetween the 3^(rd) and 4^(th) zone (the pre-heat zone and the soak zone)of the reflow soldering oven 10, a second IR camera assembly 62 b ispositioned between the 6^(th) and 7^(th) zone (the soak zone and thespike zone), and a third IR camera assembly 62 c is positioned betweenthe 9^(th) and 10^(th) zone (the spike zone and the cooling zones). Itshould be understood that the IR camera assemblies 62 can be deployedanywhere within the reflow soldering oven 10 to optimize the performanceof the reflow soldering oven.

Each IR camera assembly 62 is strategically deployed to measure thetemperature of a circuit board assembly 44 as it passes between zones toensure that the circuit board assembly is properly conditioned prior toprocessing. The information obtained from each IR camera assembly 62 iscommunicated to the controller 50, which is configured to provide closedloop processing of subsequent circuit board assemblies passing throughthe reflow soldering oven 10.

Referring additionally to FIGS. 4 and 5 , for the reflow soldering ovenapplication, each IR camera assembly 62 includes a shroud 64 that ismounted on a top wall 66 of the chamber 12 of the reflow soldering oven10. The shroud 64 is configured to extend through an opening formed inthe top wall 66 of the chamber 12 to enable a temperature of the tunnelto be sensed by the IR camera assembly 62. The support structure furtherincludes a support bracket 68 mounted on the shroud 64 on top of theshroud. The support bracket 68 includes a port 70 to connect to a sourceof nitrogen (N₂) to provide an inert atmosphere within the shroud 64.The support bracket 68 further includes an input port 72 to connect asensor to the support bracket.

The IR camera assembly 62 further includes a temperature sensorembodying an IR camera 74, which is supported in an operating positionby the support bracket 68. A cable 76 is secured to the input port 72 toconnect the IR camera 74 to the controller 50. As mentioned above, anytype of temperature sensor can be employed to measure temperatures ofcircuit board assemblies traveling within the tunnel (chamber 12) of thereflow soldering oven 10. The IR camera 74 is configured to have a fieldof view that is directed through the shroud 64 to the tunnel (chamber12) of the reflow soldering oven 10. The arrangement is such that the IRcamera 74 of the IR camera assembly 62 is configured to detecttemperatures of circuit board assemblies travelling in the tunnel(chamber 12) of the reflow soldering oven 10 and communicating thisinformation to the controller 50. The data obtained from the heatdetection system 60 can be used for a variety of purposes, which will bedescribed in greater detail below.

Referring to FIG. 6 , an alternative embodiment of the sensor assemblyis generally indicated at 80. As shown, the sensor assembly 80 includesa gantry 82 and a temperature sensor embodying an IR camera 84, which isconnected to the gantry and the controller 50. The arrangement is suchthat the gantry 82 is configured to move the IR camera 84 under thecontrol of the controller 50 along a width of the tunnel (chamber 12) toobtain temperature data across a width of the printed circuit boardassembly as the printed circuit board assembly passes through the reflowsoldering oven 10. The sensor assembly 80 further may include a shroud(not shown) to maintain the IR camera 84 in an inert (clean) atmosphere.

Wave Solder Machine

In a wave solder process, there are several process steps. There is afluxing step in which the printed circuit board assembly is cleaned byspraying a flux on the solder side (bottom) of the printed circuit boardassembly. After the flux is applied, the printed board assembly istransported to a preheat unit. The preheat unit can embody differentconcepts, such as convection or radiation heaters. The goal is to heatthe printed circuit board assembly to a pre-defined temperature that istypically measured on the solder destination side (topside board). Theflux is activated, by the preheaters and the circuit board assembly iswarm so the solder will not solidify until it achieved the topsideboard. The printed circuit board assembly enters the wave of solder. Thesoldering process consists of a heated tank of solder, which ismaintained at a required temperature for the soldering process. Withinthe tank, a wave of solder is set up and the printed circuit boardsassembly passes over the solder wave so that the underside of thecircuit board assembly contacts the solder wave.

The temperature of the circuit board assembly during preheating istypically measured with a pyrometer. This is usually done after thecircuit board assembly passes through the last preheat unit, just beforeentering the solder wave station. However, the spot of a pyrometer islimited so the data is covers only one small area of the total board.

Embodiments of the heat detection system having an IR camera is capableof scanning the entire printed circuit board assembly to obtaintemperature data from the printed circuit board assembly.

Embodiments of the heat detection system includes an IR camera with thewave solder machine after the last preheat unit. The data provided bythe IR camera can be used for closed loop process control. When the IRcamera is installed above the printed circuit board assembly in thepreheat unit, the IR camera can provide information to modify thepreheaters of the unit in such way that a specified temperature isachieved for the following boards before entering the wave solderingstation. As a result, the printed circuit board assembly can achieve anoptimal temperature when the printed circuit board assembly is soldered,which will minimize the risk for defects. The data will be recorded andin combination with board identification (like barcode or RFID) the datacan be used for traceability which can be correlated to defects duringassembly or field failures.

Referring to FIG. 7 , an exemplary wave solder machine, generallyindicated at 100, is used to perform a wave solder application on aprinted circuit board assembly. As mentioned above, the wave soldermachine 100 is one of several machines in a printed circuit boardfabrication/assembly line. As shown, the wave solder machine 100includes a housing or frame 102 adapted to house the components of themachine. The arrangement is such that a conveyor 104 delivers printedcircuit board assemblies 44 to be processed by the wave solder machine100.

Upon entering the wave solder machine 100, each circuit board assembly44 travels along an inclined path (e.g., six degrees with respect tohorizontal) along the conveyor 104 through a tunnel 106, which includesa fluxing station, generally indicated at 108, and a pre-heatingstation, generally indicated at 110, to condition the printed circuitboard assembly for wave soldering. Once conditioned (i.e., heated), thecircuit board assembly 44 travels along the conveyor 104 to a wavesoldering station, generally indicated at 112, to apply solder materialto the printed circuit board assembly. A controller 114 is provided toautomate the operation of the several stations of the wave soldermachine 100, including but not limited to the fluxing station 108, thepre-heating station 110, and the wave soldering station 112, in thewell-known manner.

As with the controller 50 associated with the reflow soldering oven 10,the controller 114 for the wave solder machine 100 may be configured touse a personal computer having a suitable operating system, such as aMicrosoft Windows® operating system provided by Microsoft Corporation,with application specific software to control the operation of the wavesolder machine. The controller 114 may be networked with a mastercontroller that is used to control a production line for fabricatingcircuit boards. Similar to reflow soldering oven 10, the informationobtained by the heat detection system can be used by the controller 114to optimize the performance of the wave solder machine 100. Thisoptimization would include an elimination of warpage and the better andmore reliable securement of electronic components on the circuit boardassembly.

Referring to FIG. 8 , the fluxing station 108 is configured to applyflux to the printed circuit board assembly as it travels on the conveyor104 through the wave solder machine 100. The pre-heating station 110includes several pre-heaters (e.g., pre-heaters 110 a, 110 b, 110 c),which are designed to incrementally increase the temperature of theprinted circuit board assembly as it travels along the conveyor 104through the tunnel 106 to prepare the printed circuit board assembly forthe wave soldering process. The wave soldering station 112 includes awave solder nozzle assembly in fluid communication with a reservoir ofsolder material. A pump is provided within the reservoir to delivermolten solder material to the wave solder nozzle assembly from thereservoir. Once soldered, the printed circuit board assembly exits thewave solder machine 100 via the conveyor 104 to another station providedin the fabrication line, e.g., a pick-and-place machine.

In some embodiments, the wave solder machine 100 further may include aflux management system, generally indicated at 116, to remove volatilecontaminants from the tunnel 106 of the wave solder machine. As shown inFIG. 2 , the flux management system 116 is positioned below thepre-heating station 110. In one embodiment, the flux management system116 is supported by the housing 102 within the wave solder machine 100,and is in fluid communication with the tunnel 106, which isschematically illustrated in FIG. 2 . The flux management system 116 isconfigured to receive contaminated gas from the tunnel 106, treat thegas, and return clean gas back to the tunnel. The flux management system116 is particularly configured to remove volatile contaminants from thegas, especially in inert atmospheres.

Referring to FIGS. 9 and 10 , the wave solder machine 100 includes aheat detection system that is configured to detect heat within the zonesof the machine, such as between the preheating station 110 and the wavesoldering station 112. The heat detection system includes a sensorassembly embodying an IR camera assembly, generally indicated at 120,which is strategically deployed to measure the temperature of a circuitboard assembly 44 as it passes between zones to ensure that the circuitboard assembly is properly conditioned prior to processing. Theinformation obtained from the IR camera assembly 120 is communicated tothe controller 114, which is configured to provide closed loopprocessing of subsequent circuit board assemblies passing through thewave solder machine 100.

For the wave solder machine application, the IR camera assembly 120includes a support structure having a mounting plate 122 that ispositioned on a top of the tunnel 106 of the wave solder machine 100 anda shroud 124 that is mounted on the mounting plate. The shroud 124 isconfigured to surround an opening within the mounting plate 122 toenable a temperature of the tunnel 106 to be sensed by the IR cameraassembly. The support structure further includes a support bracket 126mounted on the shroud 124 on top of the shroud. The support bracket 126includes a port 128 to connect to a source of nitrogen (N₂) to providean inert atmosphere within the shroud. The support bracket 126 furtherincludes an input port 130 to connect a sensor to the support bracket.

The IR camera assembly 120 further includes an IR camera 132 supportedin an operating position by the support bracket 126. A cable 134 issecured to the input port 130 to connect the IR camera 132 to thecontroller 114. As mentioned above, any type of temperature sensor canbe employed to measure temperatures of circuit board assemblies withinthe tunnel 106 of the wave solder machine 100. The IR camera 132 isconfigured to have a field of view that is directed through the shroud124 to the tunnel 106 of the wave solder machine 100. The arrangement issuch that the IR camera 132 of the IR camera assembly 120 is configuredto detect temperatures of circuit board assemblies within the tunnel 106of the wave solder machine 100 and communicating this information to thecontroller 114.

Selective Solder Machine

In a selective solder process, there are several process steps. Firstly,there is a fluxing station in which the printed circuit board assemblyis cleaned by spraying a flux on a solder side (bottom) of the printedcircuit board assembly. After the flux is applied, the printed boardassembly is transported to a preheat unit. The preheat unit can beconfigured to include different heating concepts, such as convection orradiation heaters. An objective of this process step is to heat theprinted circuit board assembly to a pre-defined temperature that istypically measured on the solder destination side (top) of the printedcircuit board assembly. The flux is activated, and the printed circuitboard assembly is warm so the solder will not solidify until theselective solder process is performed. Prior to implementing the heatdetection system of the present disclosure, the temperature of theprinted circuit board assembly during preheating can be measured with apyrometer, which produces very limited heat information about theprinted circuit board assembly.

After preheating, the printed circuit board assembly is transported tothe solder area where one of two solder processes can be performed. Inone solder process, solder is applied with a small solder nozzleconfigured to perform a point-to-point solder process. In another solderprocesses, solder is applied by a multi-wave plate in which the solderjoints are made with one dip.

Embodiments of the heat detection system may include an IR camera (2D or3D) into the selective solder process. The data provided by this cameracan be used for closed loop process control. When a camera is installedabove the printed circuit board assembly in the preheat process, thetemperature data obtained from the camera can provide information tomodify the power of the unit in such way that a specified temperature isachieved when the selective solder machine is ready to transport theboard to the soldering station. As a result, the printed circuit boardassembly can achieve an optimal temperature when it is soldered, whichwill minimize the risk for defects. The data can be recorded and incombination with board identification, such as barcode or RFID, the datacan be used for traceability that can be correlated to defects duringassembly or field failures.

An IR scanner can also be implemented in the solder station. For amulti-wave dip process, a 2D or 3D camera can be configured to measurethe temperature of the solder joints. Such a configuration can identifywhether the solder is solidified (below melting point) before theprinted circuit board assembly is moved to avoid stress in the solderjoint. Also, this data can be used for process optimization as well astraceability purposes.

For point-to-point solder processes, an implementation of an IR scannerabove the solder station can benefit to record the conditions of theprinted circuit board assembly and verify that the temperatures arewithin a tolerance range of temperatures. This information can be usedto reduce defects and have a better process control.

Other Aspects of the Heat Detection System

In some embodiments, the support bracket includes an IR camera glass toprotect the IR camera. Referring to FIG. 9 , a lens 140 is provided toprotect the IR camera 132. Although shown with the IR camera assembly120 of wave solder machine 100, it should be understood that the lens140 or camera glass can be provided with the IR camera assembly 62associated with the reflow soldering oven 10. Other types of materialsto create a protective cover may also be provided. The IR camera glassis positioned so that pressurized air is moved across the IR cameraglass to create an “air curtain” thereby preventing obstruction of theIR camera. In one embodiment, a moving film can be provided to protectthe IR camera.

The lens 140 can be applied to the IR camera 74 associated with thereflow soldering oven 10.

In some embodiments, the shroud can be configured to be connected toanother inert source of fluid.

In some embodiments, the shroud can be configured to a source of fluidthat is temperature controlled to protect the IR camera.

In some embodiments, the support bracket can be configured to mount theIR camera at a desired height and a desired orientation to achieve afull field of view. In the shown configuration, the IR camera is mountedon the top of the tunnel of the reflow soldering oven. However, the IRcamera can be mounted on the side of the tunnel of the reflow solderingoven. With side mounting, mirrors can be employed to view the top andthe bottom of the circuit boards passing through the tunnel.

In some embodiments, the IR camera can be mounted on a support structurethat serves as a gantry to move the camera across the circuit board. TheIR camera can be positioned inside or outside the tunnel of the reflowsoldering oven.

In some embodiments, the IR camera assembly can include multiple IRcameras to measure two or more separate locations within a selectposition within the tunnel of the reflow soldering oven.

In some embodiments, a one-dimensional line-scan camera can be used todetect circuit board temperatures.

In some embodiments, a two-dimensional camera can be used to detectcircuit board temperatures.

In some embodiments, an existing reflow soldering oven can be updated byway of retrofit kit, including the components of the heat detectionsystem including multiple IR camera assemblies, e.g., the mountingplates, the shrouds, the support brackets, the nitrogen connections, theIR camera cables and the IR cameras. Software upgrades can be providedfor the controller of the reflow soldering oven.

In some embodiments, the heat detection system is configured with thecontroller to provide a closed loop control of the zone temperaturesusing the IR camera assemblies or other temperature detection devices.Such closed loop control enables the operator to monitor circuit boardtemperatures and locate hot spots on circuit boards, both on the topsand bottoms of circuit boards.

In some embodiments, the controller is configured with executablesoftware that enables the closed loop control of the various zones ofthe reflow soldering oven.

In some embodiments, the information obtained from the heat detectionsystem is collected and analyzed for future actions.

In some embodiments, the IR camera assemblies of the heat detectionsystem are configured to obtain temperature data at specific board levellocations and in certain zones of the reflow soldering oven.

In some embodiments, the IR camera assemblies of the heat detectionsystem are configured to provide data to the controller for processcontrol of downstream parameters associated with the production lineand/or to address equipment issues.

In some embodiments, the printed circuit boards have bar codes that arescanned by a bar code scanner, or other type of identification system,to keep track of data for each circuit board.

In some embodiments, the IR camera assemblies of the heat detectionsystem is configured to obtain temperature data used by the controllerto provide closed loop localized heating to board zones where need.Real-time zone-to-zone temperature adjustments can be made, with theobject of circuit board temperature uniformity or a desired temperatureprofile.

In some embodiments, the closed loop processing of the circuit boardscan include controlling the conveyor to control conveyor speed in one ormore zones to optimize heat transfer. Fan blower speeds can also becontrolled. In one embodiment, the conveyor can include multiplesections that correspond to the multiple zones, with each conveyorsection being controlled by the controller to control the speed of theconveyor section and thus the temperature applied to the circuit board.Localized heating of the circuit board is achieved by this construction.

In some embodiments, the data obtained from the heat detection systemcan be used for a variety of purposes. For example, data can becommunicated to the customer. Data can be used to provide circuit boardtraceability in which data on a particular circuit board is correlatedto the customer. Data can be used to find hot spot zones/levels withinthe reflow soldering oven. Data can be used to optimize the performanceof the reflow soldering oven. Data can be used to provide downstreaminput of processing equipment. Data can be used to determine start andend times of scanning performed by the IR camera assemblies on circuitboards. Data can be used to generate circuit board profiles above andbelow the circuit boards to determine certain board zones or levels.Data can be used by the customer for other analytics and stored on acustomer server/network or on the cloud.

In some embodiments, the controller can be configured to achieve a scanmode to measure the temperature of all board components as the boardstravel on the conveyor through the reflow soldering oven.

In some embodiments, the heat detection system is configured to performthermal imaging during Moire analysis (strain/stress analysis) tocorrelate between temperature hot spots and warpage responses.

In some embodiments, the heat detection system is configured to find hotand cold spots during reflow soldering, wave soldering, SRT rework, andselective soldering.

In some embodiments, the heat detection system can be used to provideanalytics to improve board design and functionality.

In some embodiments, the heat detection system can be used to lowervoids in the reflow process.

In some embodiments, the heat detection system achieves enhancedtemperature control to reduce defects.

In some embodiments, the heat detection system incorporates integratedclosed loop control of zone temperatures of the reflow soldering oven byemploying multiple infrared (IR) camera assemblies at strategiclocations to reduce warpage, identify hotspots, determine componentoverheating, obtain profile validation and reduce voids.

In some embodiments, the heat detection system is configured to includeauto-sensing equipment having settings that are self-adjusted based onambient conditions and the product being made, thereby increasingvisibility, productivity, traceability and response times while loweringcosts.

In some embodiments, the heat detection system enables visibility andprescriptive real-time analytics with proactive actionable intelligenceacross the supply chain.

In some embodiments, the heat detection system increases flexibility bymanaging complexity within a closed loop system.

In some embodiments, connectivity is improved by the open architecturefor developing standard or custom interfaces and data outputs.Architecture is configured to support several MEMS.

In some embodiments, automation is improved by providing automatedchangeover and consumables replenishment to reduce operator errors andheadcount.

In some embodiments, the heat detection system is configured to achieveself-optimization by reducing operator intervention on machineparameters and providing closed loop control to drive higher yields.

In some embodiments, maintenance is improved by applying predictivemaintenance items based on actual needs of the reflow soldering oven orthe wave solder machine. Also, the improved maintenance replaces orreduces planned time based on maintenance.

In some embodiments, the controller associated with the reflow solderingoven or the wave solder machine includes a controller that is adapted tocontrol the operation of the oven or machine based on operationalparameters obtained by the controller. The controller can be configuredto communicate with a controller associated with a production line. Inone embodiment, the controller can be configured to communicate withanother controller, e.g., a controller associated with the productionline, over a controller area network (CAN) Bus or other type of network.In other embodiments, a master controller may be provided to control theoperation of the controllers of the individual pieces of equipmentassociated with the production line. The controller may include adisplay, which is operably coupled to the controller. The display isadapted to display the operational parameters of the reflow solderingoven or the wave solder machine, such as, but not limited to,temperature data through zones of the oven or machine or data associatedwith solder levels of the machine. Suitable sensors may be provided toacquire such information. Alternatively, or in addition to the foregoingembodiment, the operational parameters may be displayed on the displayprovided within the reflow soldering oven, the display provided withinthe wave solder machine, and/or a display associated with the productionline.

In other embodiments, material identification for items, such as circuitboards, traveling through the reflow soldering oven or the wave soldermachine, can include a device to manipulate the item and a scanner toscan and identify the item. For example, the reflow soldering oven orthe wave solder machine can be configured to include a pinch wheel torotate the circuit board to align a code or predetermined identificationmark provided on the circuit board with scanner provided on the oven ormachine. The system is configured to tie material identificationassociated with the circuit board to a recipe, production time, etc.,for the reflow soldering oven or the wave solder machine. In oneembodiment, a barcode to identify the items can be implemented. Forexample, the barcode can include a 1D scanner for UPC codes, a 2Dscanner for QRC codes, a printed label applied on the item or a laseretched label etched on the item. In another embodiment, an RFID systemto identify the items can be implemented. For example, the RFID systemcan include an RFID tag applied to the item and an RFID readerassociated with the reflow soldering oven or the wave solder machine.With an RFID system, line-of-site between the reader and the item is notrequired. Moreover, scanning is not required to identify all itemswithin the movable cart. In another embodiment, an imaging or visionsystem to identify the items can be implemented.

In some embodiments, a database is provided to keep track of itemsprocessed through the reflow soldering oven or the wave solder machine.In one embodiment, the database may include an open application (App)architecture and be configured to push data to the reflow soldering ovenor the wave solder machine. The oven or machine can be configured tocommunication with the oven or machine to push/pull data to the oven ormachine and/or the production line or configured to communicate with theproduction line directly. The database can include job information ormaterial information. The database further can communicate with amanufacturing execution system (MES) associated with the productionline, the reflow soldering oven and/or the wave solder machine. The MESsystem can be configured to know which materials are required for aproduction run. The movable cart can be configured to communicate withthe MES system to adjust delivery of items to the reflow soldering ovenor the wave solder machine.

The database further can be configured to retrieve information aboutitems based on identification, e.g., a barcode number. In oneembodiment, a central management system can be provided in which thereflow soldering oven or the wave soldering machine is programmed toaccept material coming from movable cart. The reflow soldering oven orthe wave solder machine is programmed to update the database to processcircuit boards through the oven or machine from a network, which is tiedback to the MES system.

The database further can be configured to store additional information,such as temperature data, numbers of circuit boards processed, and/orconsumption of materials associated with the reflow soldering oven orthe wave solder machine. The database can be configured to storeinformation locally or remotely, and can be configured to store dataassociated with one or more production runs.

The database can be configured to share prediction data when newproduction runs are contemplated or programmed. For example, withrespect to storing information related to temperature processingefficiency, the database can be configured to perform one or more of thefollowing: store information on temperature zone data, numbers and typesof circuit boards processed, when paste consumable items needreplenishment; trigger an alarm and/or a report; signal to an inventorycontrol system associated with the reflow soldering oven, the wavesolder machine and/or the production line; perform analytics onconsumable usage based on operating parameters and actual use andupstream/downstream equipment activity; predict changeout ormaintenance; and correlate over multiple sites to predict futureproduction run parameters.

The database can be configured to store data associated with lottraceability. In addition, RFID or mechanical keying of a circuit boardis provided to ensure correctalignment/orientation/direction/front-back/top-bottom when these itemsare inserted into the reflow soldering oven or the wave solderingmachine for processing. A low-cost reader can perform this function.

Controller Feedback

FIG. 11 depicts an example system 200 according to various embodiments.System 200 includes a tunnel 202 within a chamber housing 203 having aconveyor 204 and a plurality of temperature sensors 210 (depicted astemperature sensors 210 a, 210 b, 210 c), heaters 212 (depicted asheaters 212 a, 212 b), and blowers 214 (depicted as blowers 214 a, 214b). System 200 also includes a controller 250. It should be understoodthat the term “blower” may include any kind of device configured to moveair, including a fan.

In some embodiments, system 200 may be a single apparatus includedwithin a single housing. In other embodiments, controller 250 may behoused separately from the chamber housing 203.

In some embodiments, the chamber housing 203 may be part of a reflowoven 10. In other embodiments, the chamber housing 203 may be part of awave solder machine housing 102. In yet other embodiments, the chamberhousing 203 may be part of a selective solder machine housing.

An electronic substrate or circuit board assembly 44 passes through thetunnel 202 along a conveyor 204 (e.g., conveyor 46, 104) driven by amotor (or other drive mechanism) 205 through temperature detection zones216 (depicted as temperature detection zones 216 a, 216 b, 216 c) andprocessing zones 218 (depicted as processing zones 218 a, 218 b).

Circuit board assembly 44 includes a plurality of electronic components206 mounted on an underlying circuit board. Electronic components 206may include, for example, integrated circuit chips 207, solder 208, andother components such as traces (not depicted) as well as the underlyingsubstrate itself. It should be understood that although only one circuitboard assembly 44 is depicted as passing through tunnel 202, multiplecircuit board assemblies 44 may pass through the tunnel 202 at a time.In some embodiments, several circuit board assemblies 44 may passthrough side-by-side as well as front-to-back.

In some embodiments, processing zones 218 may include, for example, oneor more pre-heat zones 14, 16, 18, soak zones 20, 22, 24, spike zones30, 32, 34, 36, and cooling zones 38, 40, 42 as described above withreference to reflow soldering oven 10. Each processing zone 218 mayinclude one or more of a heater 212 (e.g., a top heater 26 or bottomheater 28) and blower 214 and any other processing component, dependingon the purpose of that processing zone 218.

Each temperature detection zone 216 includes one or more temperaturesensor 210 (e.g., an IR camera assembly 62). A temperature sensor 210Nmay be configured to detect temperatures of the various differentcomponents of the circuit board assemblies 44 that pass through itscorresponding temperature detection zone 216N.

Although temperature detection zones 216 and processing zones 218 aredepicted separately, in some embodiments, a temperature detection zone216 may be combined with a processing zone 218. Although only threetemperature detection zones 216 and two processing zones 218 aredepicted, there may be any number of temperature detection zones 216 andprocessing zones 218, preferably at least two of each. Althoughtemperature detection zones 216 and processing zones 218 are depicted asalternating, there may be multiple different processing zones 218 thatintervene between successive temperature detection zones 216.

Controller 250 (e.g., controller 50, 114) is configured to control theheaters 212 and/or blowers 214 (and any other processing components) ofprocessing zones 218 and receive feedback from the temperature sensors210 of temperature detection zones 216. In some embodiments, controller250 may also control the drive speed of conveyor 204.

Controller 250 may be any kind of computing device, such as, forexample, a personal computer, laptop, workstation, server, enterpriseserver, tablet, smartphone, integrated system, etc. Controller 250includes processing circuitry 236, communications interface circuitry234, and memory 240. In some embodiments, controller 250 may alsoinclude user interface (UI) circuitry 238 for connecting to a UI inputdevice (not depicted) and a display device (not depicted). Controller250 may also include various additional features as is well-known in theart, such as, for example, interconnection buses, etc.

Processing circuitry 236 may include any kind of processor or set ofprocessors configured to perform operations, such as, for example, amicroprocessor, a multi-core microprocessor, a digital signal processor,a system on a chip (SoC), a collection of electronic circuits, a similarkind of controller, or any combination of the above.

Communications interface circuitry 234 may include one or morenetworking devices (e.g., Ethernet cards, cellular modems, Fibre Channel(FC) adapters, InfiniBand adapters, wireless networking adapters, etc.)and/or local bus ports (e.g., USB, Firewire, serial bus, parallel bus,etc.) for connecting to heaters 212, blowers 214, temperature sensors210, and/or other controllable devices of the chamber housing 203, suchas, for example, a conveyor motor 205.

UI circuitry 238 may include any circuitry needed to communicate withand connect to one or more user input devices and display screens. UIcircuitry 238 may include, for example, a keyboard controller, a mousecontroller, a touch controller, a serial bus port and controller, auniversal serial bus (USB) port and controller, a wireless controllerand antenna (e.g., Bluetooth), a graphics adapter and port, etc.

Memory 240 may include any kind of digital system memory, such as, forexample, random access memory (RAM). Memory 240 stores an operatingsystem (OS) (not depicted, e.g., a Linux, UNIX, Windows, MacOS, orsimilar operating system) and various drivers and other applications andsoftware modules configured to execute on processing circuitry 236.

Memory 240 stores a set of modules 282, 284, 290, 296, which areconfigured to execute on processing circuitry 236.

Feedback module 282 is configured to receive temperature readings suchas temperature maps 280 (depicted as zone temperature maps 280 a, 280 b,280 c) from temperature sensors 210 as one or more circuit boardassemblies 44 passes through tunnel 202 along conveyor 204. In anembodiment, zone a temperature map 280 a is a 2-dimensional (or3-dimensional) map of temperatures within temperature detection zone 216a as recorded by an IR camera assembly 62 of temperature sensor 210 a,while zone b temperature map 280 b is a 2-dimensional (or 3-dimensional)map of temperatures within temperature detection zone 216 b as recordedby an IR camera assembly 62 of temperature sensor 210 b, and zone ctemperature map 280 c is a 2-dimensional (or 3-dimensional) map oftemperatures within temperature detection zone 216 c as recorded by anIR camera assembly 62 of temperature sensor 210 c.

In some embodiments, feedback module 282 may also be configured totranslate each zone temperature map 280X into one or morecomponent-level temperature maps 281 (depicted as component-leveltemperature maps 281-1, 281-2, . . . ) that includes a temperature ofevery electronic component 206 on a particular circuit board assembly 44passing through zone X. In some embodiments, component-level temperaturemaps 281 may record both a lowest and a highest temperature measured foreach component 206. The component-level temperature maps 281 may becreated with reference to a board configuration 260 input by a user viaUI circuitry 238. Board configuration 260 may include the dimensions ofthe design of the particular circuit board assembly 44 as well as alocation, size, and shape of each component 206 of the design of theparticular circuit board assembly 44.

Comparison module 284 is configured to compare the component-leveltemperature maps 281 to one or more expected component-level temperaturemaps 285 (depicted as expected maps 285 a, 285 b, . . . ). An expectedcomponent-level temperature map 285X defines an expected temperaturerange for each component 206 of a design of a particular circuit boardassembly 44 at a particular temperature detection zone 216X.

Optimization module 290 is configured to generate a set of adjustments294 to be made to a set of current settings 270 based on the differencesdetected by the comparison module 284. Current settings 270 may include,for example, a conveyor speed 272 as well as a temperature setting 274and a blower speed 276 for each processing zone 218 (depicted astemperature setting 274 a and blower speed 276 a for processing zone 218a). Adjustments 294 are communicated by control module 296 to thevarious devices such as heaters 212, blowers 214, and the conveyor motor205 for adjustment. Adjustments 294 are also used to update the currentsettings 270.

In some embodiments, optimization module 290 includes a trained machinelearning model (MLM) 292. Trained MLM 292 may be any kind of machinelearning model, such as a neural network (e.g., ResNet50, EfficientNetB7, EfficientNet, MobileNetV3, etc.), Bayesian network, support-vectormachine, decision tree, random forest, regression model, etc. TrainedMLM 292 may include as many input nodes (not depicted) as there arecurrent settings 270 plus 2-dimensional or 3-dimensional input nodes fortemperature maps 280 or 281 or a map (not depicted) of the variancescalculated by the comparison module 284. Trained MLM 292 may alsoinclude as many output nodes (not depicted) as there are currentsettings 270 that are adjustable. In embodiments in which trained MLM292 is a neural network or a Bayesian network, it may also include oneor more hidden layers having a plurality of hidden nodes (not depicted).In example embodiments, there may be between 10 and 1 billion hiddennodes.

In some embodiments, Trained MLM 292 may initially be trained by runningone or more circuit board assemblies 44 through the tunnel 202 usingsupervised learning. Before such runs, the board configurations 260 forthose circuit board assemblies 44 may also be input into training nodesof Trained MLM 292. In some embodiments, thermal characteristics 262 foreach type of component 206 may also be entered. Thermal characteristics262 for a particular type of component 206N may include the thermalconductivity, density, specific heat, and thermal diffusivity of thatparticular type of component 206N, for example. In some embodiments, amaximum safe temperature 264 (e.g., a temperature at which a board willwarp; a temperature at which a chip will fry, etc.) and a minimumworking temperature 266 for each type of component 206N may also beentered. A “working temperature” for a particular component 206N isdefined to be the maximum temperature reached by that component 206Nover the course of a run through the tunnel 202. An example minimumworking temperature 266 is the melting point of solder (or thetemperature at which the solder is guaranteed to melt enough to reliablybond).

Memory 240 may also store various other data structures used by the OS,modules 282, 284, 290, 296, Trained MLM 292, and various otherapplications and drivers. In some embodiments, memory 240 may alsoinclude a persistent storage portion. Persistent storage portion ofmemory 240 may be made up of one or more persistent storage devices,such as, for example, magnetic disks, flash drives, solid-state storagedrives, or other types of storage drives. Persistent storage portion ofmemory 240 is configured to store programs and data even while thecontroller 250 powered off. The OS, modules 282, 284, 290, 296, TrainedMLM 292, and various other applications and drivers are typically storedin this persistent storage portion of memory 240 so that they may beloaded into a system portion of memory 240 upon a system restart or asneeded. The OS, modules 282, 284, 290, 296, Trained MLM 292, and variousother applications and drivers, when stored in non-transitory formeither in the volatile or persistent portion of memory 240, each form acomputer program product. The processing circuitry 236 running one ormore applications thus forms a specialized circuit constructed andarranged to carry out the various processes described herein.

FIG. 12 illustrates an example method 300 performed by a system 200 forjoining electronic components to an electronic substrate in an apparatussuch as a reflow soldering oven 10, a wave solder machine 100, or aselective solder machine. It should be understood that any time a pieceof software (e.g., OS, modules 282, 284, 290, 296, Trained MLM 292,etc.) is described as performing a method, process, step, or function,what is meant is that a computing device (e.g., controller 250) on whichthat piece of software is running performs the method, process, step, orfunction when executing that piece of software on its processingcircuitry 236. It should be understood that one or more of the steps orsub-steps of method 300 may be omitted in some embodiments. Similarly,in some embodiments, one or more steps or sub-steps may be combinedtogether or performed in a different order. Dashed lines indicate that astep or sub-step is either optional or representative of alternateembodiments or use cases.

In some embodiments, Trained MLM 292 may initially be trained usingsupervised learning in step 305. In step 305, a plurality of circuitboard assemblies 44 having different board configurations 260, thermalcharacteristics 262, maximum safe temperatures 264, and minimum workingtemperatures 266 are transported through the tunnel 202 of the chamberhousing 203 in order to train the Trained MLM 292. Trained MLM 292 isconfigured to adjust the current settings 270 for each different type ofcircuit board assembly 44 until each component 206 of each differenttype of circuit board assembly 44 reliably reaches its minimum workingtemperature 266 (in some embodiments for at least a minimum amount oftime) (if a minimum working temperature 266 is applicable to thatcomponent 206) during a run through the tunnel 202 without exceeding themaximum safe temperature 264 for that component 206 during that run. Thethermal characteristics 262 may be used to aid in ascertaining how toadjust the current settings 270 from run to run. At the end of step 305,an initial set of current settings 270 for at least one particularcircuit board assembly 44 design is output. In some embodiments, theTrained MLM 292 may be generalizable to use for any particular circuitboard assembly 44 design given the board configuration 260, thermalcharacteristics 262, and maximum safe temperatures 264 and minimumworking temperatures 266 for each component 206 as inputs. In otherembodiments, a separate Trained MLM 292 may be generated in the trainingphase for each different circuit board assembly 44 design. In someembodiments, step 305 may be performed as an explicit training processusing test workpieces. In some embodiments, step 305 may includeprevious runs of non-test circuit board assemblies 44, allowing machinelearning to refine operation as more and more runs are performed.

In step 310, a plurality of circuit board assemblies 44 is transportedthrough a chamber housing 203 including a tunnel 202 extending throughmultiple processing zones 218. In sub-step 315, the system 200 detectstemperatures of the electronic substrates 44 passing proximate to a heatdetection system including at least one temperature sensor 210 coupledto the chamber housing 203. In some embodiments, in sub-step 316, thesystem 200 detects temperatures of a plurality of components 206 of theelectronic substrates 44 at each of a plurality of locations (e.g., atsuccessive temperature detection zones 216) along the tunnel 202 (e.g.,using an IR camera assembly 62 in each temperature detection zones 216).It should be understood that step 310 is a step of general operation,and thus it may operate in parallel or concurrently with the remainingsteps.

The remainder of method 300 may be used in different embodiments. In oneembodiment (hereinafter the “Run-by-Run embodiment” or “RBRembodiment”), associated with steps 320, 370, a first circuit boardassembly 44-1 is run through the tunnel 202 using initial currentsettings 270, and after the adjustments 294 are determined and applied,a second circuit board assembly 44-2 of the same design is run throughthe tunnel 202 using updated current settings 270. In another embodiment(hereinafter the “Real-time embodiment”), associated with steps 330,380, 390, as a particular circuit board assembly 44 is run through thetunnel 202, the current settings 270 are adjusted in real-time so thatsubsequent processing zones 218 can adjust their operation as needed.

In step 320 of the RBR embodiment, a first circuit board assembly 44-1is transported through the chamber housing 203. It should be understoodthat although only a first circuit board assembly 44-1 is mentioned,there may be several first circuit board assemblies 44-1 that runthrough the tunnel 202 simultaneously. It should be understood that step315 operates on the first circuit board assembly (or assemblies) 44-1 asit is transported through the chamber housing 203.

In step 330 of the Real-time embodiment, as a particular circuit boardassembly 44 is transported through the chamber housing 203, a first ofat least two temperature sensors (e.g., temperature sensor 210 a)detects temperatures of a plurality of components 206 of that particularcircuit board assembly 44 at a first location (e.g., within temperaturedetection zone 216 a) along the tunnel 202 (e.g., by imaging the circuitboard assembly 44 with a first IR camera assembly 62).

In step 340, feedback module 282 operating on controller 250 receivestemperature data (e.g., one or more zone temperature maps 280) from theheat detection system, the controller 250 being coupled to the multipleprocessing zones 218, a conveyor motor 205, and the heat detectionsystem (i.e., temperature sensors 210).

In the RBR embodiment, in step 340 the zone temperature maps 280 fromall the temperature detection zones 216 are received in sequence as thefirst circuit board assembly 44-1 passes through each respectivetemperature detection zone 216.

In the Real-time embodiment, in step 340 one zone temperature map 280from its respective temperature detection zone 216 is received as theparticular circuit board assembly 44-1 passes through that temperaturedetection zone 216.

In step 350, the controller 250 determines, with reference to thedetected temperatures (e.g., one zone temperature map 280 in theReal-time embodiment, all zone temperature maps 280 in the RBRembodiment) of the electronic substrate(s) 44, an adjustment 292 to atleast one of (a) a heat setting of a heating element 212 within thechamber housing 203, (b) a speed of the conveyor 204, and (c) anoperational speed of a blower 214 within the chamber housing 203.

Step 350 may include sub-steps 352, 354. In sub-step 352, comparisonmodule 284 compares each detected temperature of each component 206(e.g., with reference to one or more of the component-level temperaturemaps 281 generated from one or more of the zone temperature maps 280) ateach (in the case of the RBR embodiment) or a first (in the case of theReal-time embodiment) location (e.g., temperature detection zone 216)along the tunnel 202. Then, in sub-step 354, optimization module 290performs an optimization operation configured to adjust the currenthardware settings 270 in one or more of the processing zones 218 toreduce the set of variances calculated by the comparison module 284. Inthe case of the RBR embodiment, the adjustments 292 may affect one ormore of the processing zones 218. In the case of the Real-timeembodiment, the adjustments 292 affect one or more processing zones 218situated after the first location (e.g., processing zone 218 a after thetemperature detection zone 216 a or processing zone 218 b after thetemperature detection zone 216 b).

In some embodiments, sub-step 354 includes further sub-step 355 in whichoptimization module 290 operates the Trained MLM 292 on processingcircuitry 236 to perform the optimization.

In some embodiments, if a temperature of a particular component 206 ishigher than expected, optimization module 290 may determine theadjustment to be at least one of (1) reducing the heat setting of aheating element 212, (2) adjusting the speed of the conveyor 204, and(3) increasing the operational speed of a blower 214. In the case of theRBR embodiment, if the temperature of a particular component 206N of thefirst electronic substrate 44-1 has exceeded a maximum safe temperature264N for that component 206N in temperature detection zone 216X,optimization module 290 may determine the adjustment to be at least oneof (1) reducing the heat setting of a heating element 212 located in aprocessing zone 218 prior to the temperature detection zone 216X, (2)increasing the speed of the conveyor 204, and (3) increasing theoperational speed of a blower 214 located in a processing zone 218 priorto the temperature detection zone 216X. In the case of the Real-timeembodiment, if the temperature of a particular component 206N of theparticular electronic substrate 44 has exceeded an expected temperature(e.g., from the expected temperature map 285X) for that component 206Nin temperature detection zone 216X but has not yet exceeded the maximumsafe temperature 264N for that component 206N, optimization module 290may determine the adjustment to be at least one of (1) reducing the heatsetting of a heating element 212 located in a processing zone 218subsequent to the temperature detection zone 216X, (2) increasing ordecreasing the speed of the conveyor 204, and (3) increasing theoperational speed of a blower 214 located in a processing zone 218subsequent to the temperature detection zone 216X.

In some embodiments, if a temperature of a particular component is lowerthan expected, optimization module 290 may determine the adjustment tobe at least one of (1) increasing the heat setting of a heating element212, (2) adjusting the speed of the conveyor 204, and (3) decreasing theoperational speed of a blower 214. In the case of the RBR embodiment, ifthe temperature of a particular component 206N of the first electronicsubstrate 44-1 has not reached a minimum temperature for that soldercomponent to reliably melt for that component 206N by the end of thetunnel 202, optimization module 290 may determine the adjustment to beat least one of (1) increasing the heat setting of a heating element 212located in one or more processing zones 218, (2) decreasing the speed ofthe conveyor 204, and (3) decreasing the operational speed of a blower214 located in one or more processing zones 218. In the case of theReal-time embodiment, if the temperature of a particular component 206Nof the particular electronic substrate 44 is lower than expected (e.g.,with reference to the expected temperature map 285X) for that component206N in temperature detection zone 216X, optimization module 290 maydetermine the adjustment to be at least one of (1) increasing the heatsetting of a heating element 212 located in a processing zone 218subsequent to that temperature detection zone 216X, (2) increasing ordecreasing the speed of the conveyor 204, and (3) decreasing theoperational speed of a blower 214 located in a processing zone 218subsequent to that temperature detection zone 216X.

After step 350, in step 360, controller 250 performs the determinedadjustment(s) 294 by updating the current settings 270 and sending theadjustment(s) 294 to the appropriate devices 212, 214, 205 via controlmodule 296 and communications interface circuitry 234.

In the case of the RBR embodiment, in step 370, a second circuit boardassembly 44-2 is transported through the chamber housing 203, now usingthe updated current settings 270 after applying the adjustment(s) 292.It should be understood that although only a second circuit boardassembly 44-2 is mentioned, there may be several second circuit boardassemblies 44-2 that run through the tunnel 202 simultaneously. Itshould be understood that step 315 operates on the second circuit boardassembly (or assemblies) 44-2 as it is transported through the chamberhousing 203.

In the case of the Realtime embodiment, in step 380, the particularcircuit board assembly 44 continues to be transported through at leastone processing zone 218 of the chamber housing 203 subsequent to thefirst temperature sensor (e.g., processing zone 218 a subsequent totemperature sensor 210 a, processing zone 218 b subsequent totemperature sensor 210 b, etc.). Then, in step 390, system 200 detectstemperatures of a plurality of components 206 of that particular circuitboard assembly 44 at a second location after the processing zone 218through which it ran in step 380 (e.g., within temperature detectionzone 216 b or 216 c) along the tunnel 202 (e.g., by imaging the circuitboard assembly 44 with a second IR camera assembly 62). Operation maythen return back to step 340 as the particular circuit board assembly 44continues to run through the tunnel 202. Having thus described severalaspects of at least one embodiment of this disclosure, it is to beappreciated various alterations, modifications, and improvements willreadily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be part of thisdisclosure, and are intended to be within the spirit and scope of thedisclosure. Accordingly, the foregoing description and drawings are byway of example only. It should be understood that although variousembodiments have been described as being methods, software embodyingthese methods is also included. Thus, one embodiment includes a tangiblecomputer-readable medium (such as, for example, a hard disk, a floppydisk, an optical disk, computer memory, flash memory, etc.) programmedwith instructions, which, when performed by a computer or a set ofcomputers, cause one or more of the methods described in variousembodiments to be performed. Another embodiment includes a computerwhich is programmed to perform one or more of the methods described invarious embodiments.

Furthermore, it should be understood that all embodiments which havebeen described may be combined in all possible combinations with eachother, except to the extent that such combinations have been explicitlyexcluded.

Finally, nothing in this Specification shall be construed as anadmission of any sort. Even if a technique, method, apparatus, or otherconcept is specifically labeled as “background” or as “conventional,”Applicant makes no admission that such technique, method, apparatus, orother concept is actually prior art under 35 U.S.C. § 102 or 103, suchdetermination being a legal determination that depends upon manyfactors, not all of which are known to Applicant at this time.

What is claimed is:
 1. A method of joining electronic components to anelectronic substrate in an apparatus, the method comprising:transporting electronic substrates through a chamber housing including atunnel extending through multiple processing zones; detectingtemperatures of the electronic substrates passing proximate to a heatdetection system including at least one temperature sensor coupled tothe chamber housing; receiving temperature data from the heat detectionsystem with a controller coupled to the multiple processing zones, aconveyor, and the heat detection system; determining, by the controller,with reference to the detected temperatures of the electronicsubstrates, an adjustment to at least one of (a) a heat setting of aheating element within the chamber housing, (b) a speed of the conveyor,and (c) an operational speed of a blower within the chamber housing; andperforming the determined adjustment.
 2. The method of claim 1, wherein:determining the adjustment is performed after transporting a firstelectronic substrate through the chamber housing; and performing thedetermined adjustment is done prior to transporting a second electronicsubstrate through the chamber housing.
 3. The method of claim 2, whereindetermining the adjustment includes, in response to determining that atemperature of a component of the first electronic substrate hasexceeded a maximum safe temperature for that component, determining theadjustment to be at least one of (1) reducing the heat setting of theheating element, (2) increasing the speed of the conveyor, and (3)increasing the operational speed of the blower.
 4. The method of claim2, wherein determining the adjustment includes, in response todetermining that a temperature of a solder component of the firstelectronic substrate has not reached a minimum temperature for thatsolder component to reliably melt, determining the adjustment to be atleast one of (1) increasing the heat setting of the heating element, (2)decreasing the speed of the conveyor, and (3) decreasing the operationalspeed of the blower.
 5. The method of claim 2, wherein: the heatdetection system includes a plurality of temperature sensors arranged insequence along the tunnel; detecting temperatures includes detectingtemperatures of a plurality of components of the first electronicsubstrate at each of a plurality of locations along the tunnel;determining the adjustment includes: comparing each detected temperatureof each component at each location to an expected temperature for thatcomponent at that location, yielding a set of variances; and performingan optimization operation configured to adjust hardware settings in themultiple processing zones to reduce the set of variances.
 6. The methodof claim 5, wherein performing the optimization operation includesoperating a trained machine learning model.
 7. The method of claim 6,wherein operating the trained machine learning model includes inputting,into the trained neural network: initial hardware settings in themultiple processing zones in effect while the first electronic substratepassed through the chamber housing; a configuration of components of thefirst electronic substrate; thermal characteristics of the components ofthe first electronic substrate; a maximum safe temperature for at leastone component of the first electronic substrate; and a minimum workingtemperature for at least one component of the first electronicsubstrate.
 8. The method of claim 7, wherein the method furthercomprises training the machine learning model using supervised learningprior to transporting the first electronic substrate through the chamberhousing, wherein training the machine learning model using supervisedlearning includes transporting a plurality of electronic substrateshaving different configurations, thermal characteristics, maximum safetemperatures, and minimum working temperatures through the chamberhousing.
 9. The method of claim 5, wherein: the plurality of temperaturesensors includes a plurality of infrared (IR) cameras; and detectingtemperatures of the plurality of components of the first electronicsubstrate at each of the plurality of locations along the tunnelincludes imaging the plurality of components of the first electronicsubstrate at each of the plurality of locations along the tunnel with anIR camera of the plurality of IR cameras.
 10. The method of claim 1,wherein: the heat detection system includes at least two temperaturesensors arranged in sequence along the tunnel, at least one processingzone intervening between the at least two temperature sensors; and for aparticular electronic substrate being transported through the chamberhousing: determining the adjustment for the particular electronicsubstrate is performed after detecting temperatures of a plurality ofcomponents of the particular electronic substrate at a first locationalong the tunnel by a first of the at least two temperature sensors; andperforming the determined adjustment is done prior to transporting theparticular electronic substrate through the at least one processingzone.
 11. The method of claim 10, wherein: the at least two temperaturesensors include a first infrared (IR) camera and a second IR camera; anddetecting temperatures of the plurality of components of the particularelectronic substrate at the first location along the tunnel includesimaging the plurality of components of the first electronic substrate atthe first location along the tunnel with the first IR camera; the methodfurther includes detecting temperatures of the plurality of componentsof the particular electronic substrate at a second location along thetunnel after transporting the particular electronic substrate throughthe at least one processing zone by imaging the plurality of componentswith the second IR camera.
 12. An apparatus configured to joinelectronic components to an electronic substrate, the apparatuscomprising: a chamber housing including a tunnel extending throughmultiple processing zones; a conveyor configured to transport electronicsubstrates in the tunnel through the multiple processing zones; a heatdetection system including at least one temperature sensor coupled tothe chamber housing, the at least one temperature sensor beingconfigured to detect temperatures of the electronic substrates passingproximate to the at least one temperature sensor; and a controllercoupled to the multiple processing zones, the conveyor, and the heatdetection system, the controller being configured to: receivetemperature data from the heat detection system; determine, withreference to the detected temperatures of the electronic substrates, anadjustment to at least one of (a) a heat setting of a heating elementwithin the chamber housing, (b) a speed of the conveyor, and (c) anoperational speed of a blower within the chamber housing; and performingthe determined adjustment.
 13. The apparatus of claim 12, wherein: thecontroller is configured to determine the adjustment after transportinga first electronic substrate through the chamber housing; and thecontroller is configured to perform the determined adjustment prior totransporting a second electronic substrate through the chamber housing.14. The apparatus of claim 13, wherein determining the adjustmentincludes, in response to determining that a temperature of a componentof the first electronic substrate has exceeded a maximum safetemperature for that component, determining the adjustment to be atleast one of (1) reducing the heat setting of the heating element, (2)increasing the speed of the conveyor, and (3) increasing the operationalspeed of the blower.
 15. The apparatus of claim 13, wherein determiningthe adjustment includes, in response to determining that a temperatureof a solder component of the first electronic substrate has not reacheda minimum temperature for that solder component to reliably melt,determining the adjustment to be at least one of (1) increasing the heatsetting of the heating element, (2) decreasing the speed of theconveyor, and (3) decreasing the operational speed of the blower. 16.The apparatus of claim 13, wherein: the heat detection system includes aplurality of temperature sensors arranged in sequence along the tunnel;detecting temperatures includes detecting temperatures of a plurality ofcomponents of the first electronic substrate at each of a plurality oflocations along the tunnel; determining the adjustment includes:comparing each detected temperature of each component at each locationto an expected temperature for that component at that location, yieldinga set of variances; and performing an optimization operation configuredto adjust hardware settings in the multiple processing zones to reducethe set of variances.
 17. The apparatus of claim 16, wherein performingthe optimization operation includes operating a trained machine learningmodel.
 18. The apparatus of claim 16, wherein: the plurality oftemperature sensors includes a plurality of infrared (IR) cameras; anddetecting temperatures of the plurality of components of the firstelectronic substrate at each of the plurality of locations along thetunnel includes imaging the plurality of components of the firstelectronic substrate at each of the plurality of locations along thetunnel with an IR camera of the plurality of IR cameras.
 19. Theapparatus of claim 12, wherein: the heat detection system includes atleast two temperature sensors arranged in sequence along the tunnel, atleast one processing zone intervening between the at least twotemperature sensors; and for a particular electronic substrate beingtransported through the chamber housing: the controller is configured todetermine the adjustment for the particular electronic substrate afterdetecting temperatures of a plurality of components of the particularelectronic substrate at a first location along the tunnel by a first ofthe at least two temperature sensors; and the controller is configuredto perform the determined adjustment prior to transporting theparticular electronic substrate through the at least one processingzone.
 20. The apparatus of claim 19, wherein: the at least twotemperature sensors include a first infrared (IR) camera and a second IRcamera; and detecting temperatures of the plurality of components of thefirst electronic substrate at the first location along the tunnelincludes imaging the plurality of components of the first electronicsubstrate at the first location along the tunnel with the first IRcamera; the second IR camera is configured to detect temperatures of theplurality of components of the particular electronic substrate at asecond location along the tunnel after transporting the particularelectronic substrate through the at least one processing zone by imagingthe plurality of components.
 21. A computer program product comprising anon-transitory computer-readable medium storing instructions, which,when executed by processing circuitry of a controller device coupled toan apparatus configured to join electronic components to an electronicsubstrate, causes the controller device to: operate the apparatus totransport electronic substrates through a chamber housing including atunnel extending through multiple processing zones; operate theapparatus to detect temperatures of the electronic substrates passingproximate to a heat detection system including at least one temperaturesensor coupled to the chamber housing; receive temperature data from theheat detection system; determining, with reference to the detectedtemperatures of the electronic substrates, an adjustment to at least oneof (a) a heat setting of a heating element within the chamber housing,(b) a speed of a conveyor within the chamber housing, and (c) anoperational speed of a blower within the chamber housing; and operatethe apparatus to perform the determined adjustment.